Exam 3 BIOL 1406, Fall 2012 HCC Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using A) a phase-contrast light microscope. B) a confocal fluorescence microscope. C) a scanning electron microscope. D) a super-resolution fluorescence microscope. E) a transmission electronic microscope. 1) 2) The advantage of light microscopy over electron microscopy is that 2) A) light microscopy provides for higher resolving power than electron microscopy. B) light microscopy provides higher contrast than electron microscopy. C) light microscopy provides for higher magnification than electron microscopy. D) specimen preparation for light microcopy does not produce artifacts. E) light microscopy allows one to view dynamic processes in living cells. 3) What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division? A) light microscopy B) super-resolution fluorescence microscopy C) transmission electron microscopy D) confocal fluorescence microscopy E) scanning electron microscopy 3) 4) All of the following are part of a prokaryotic cell except 4) A) a cell wall. B) a plasma membrane. C) ribosomes. D) DNA. E) an endoplasmic reticulum. 5) Which of the following is a major cause of the size limits for certain types of cells? 5) A) rigid cell walls that limit cell size expansion B) evolutionary progression in cell size; more primitive cells have smaller sizes C) the difference in plasma membranes between prokaryotes and eukaryotes D) the need for a surface area of sufficient area to support the cell's metabolic needs E) limitation on the strength and integrity of the plasma membrane as cell size increases 6) Prokaryotes are classified as belonging to two different domains. What are the domains? 6) A) Bacteria and Archaea B) Bacteria and Eukarya C) Archaea and Protista D) Bacteria and Fungi E) Bacteria and Protista 1
7) A cell with a predominance of free ribosomes is most likely 7) A) constructing an extensive cell wall or extracellular matrix. B) enlarging its vacuole. C) producing primarily cytoplasmic proteins. D) producing primarily proteins for secretion. E) digesting large food particles. 8) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? A) dehydration B) catabolism C) metabolism D) anabolism 8) 9) Which structure is the site of the synthesis of proteins that may be exported from the cell? 9) A) Golgi vesicles B) free cytoplasmic ribosomes C) rough ER D) plasmodesmata E) lysosomes 2
10) According to this figure, which of the following is large enough to see in the light microscope? 10) A) viruses B) mitochondria C) proteins D) atoms 11) Which of the following is (are) true for anabolic pathways? 11) A) They do not depend on enzymes. B) They are usually highly spontaneous chemical reactions. C) They consume energy to build up polymers from monomers. D) They consume energy to decrease the entropy of the organism and its environment. E) They release energy as they degrade polymers to monomers. 3
12) The function of chloroplasts is 12) A) cellular respiration. B) intracellular digestion. C) photosynthesis. D) lipid synthesis. 13) Microfilaments differ from microtubules in that microfilaments 13) A) are found only in plants, whereas microtubules are found in both plant and animal cells. B) are mainly composed of actin, whereas microtubules are composed of tubulin. C) help to anchor organelles, whereas microtubules primarily function to help cells change shape and move. D) are thicker than microtubules. 14) Resolution is the 14) A) size of an image. B) ability of an optical instrument to magnify an image. C) ability of an optical instrument to show two close objects as separate. D) distance between the lenses of a microscope. 15) Which of the following statements about the cytoskeleton is false? 15) A) The cytoskeleton is composed of three types of fibers: microfilaments, microtubules, and intermediate filaments. B) The cytoskeleton plays an important role in amoeboid motion. C) Once laid down, the elements of the cytoskeleton are fixed and remain permanently in place. D) The cytoskeleton helps to support cells. 16) Which part of the mitochondrion shown enhances its ability to produce ATP by increasing the surface area of a mitochondrial membrane? 16) A) structure A B) structure B C) structure C D) structure D 17) Which of the following is a statement of the first law of thermodynamics? 17) A) The entropy of the universe is constant. B) Energy cannot be transferred or transformed. C) The entropy of the universe is decreasing. D) Energy cannot be created or destroyed. E) Kinetic energy is stored energy that results from the specific arrangement of matter. 4
18) Which of the following statements is representative of the second law of thermodynamics? 18) A) Heat represents a form of energy that can be used by most organisms to do work. B) Cells require a constant input of energy to maintain their high level of organization. C) Every energy transformation by a cell decreases the entropy of the universe. D) Without an input of energy, organisms would tend toward decreasing entropy. E) Conversion of energy from one form to another is always accompanied by some gain of free energy. 19) Which of the following is an example of potential rather than kinetic energy? 19) A) the muscle contractions of a person mowing grass B) water rushing over Niagara Falls C) the flight of an insect foraging for food D) light flashes emitted by a firefly E) a molecule of glucose 20) Which of the following is the smallest closed system? 20) A) a cell B) an ecosystem C) Earth D) an organism E) the universe 21) Which of the following is true for all exergonic reactions? 21) A) The products have more total energy than the reactants. B) A net input of energy from the surroundings is required for the reactions to proceed. C) The reaction proceeds with a net release of free energy. D) The reactions are rapid. 22) A chemical reaction that has a positive G is correctly described as 22) A) endergonic. B) enthalpic. C) spontaneous. D) endothermic. E) exothermic. 23) Why is ATP an important molecule in metabolism? 23) A) Its hydrolysis provides an input of free energy for exergonic reactions. B) Its terminal phosphate bond has higher energy than the other two. C) It is one of the four building blocks for DNA synthesis. D) It provides energy coupling between exergonic and endergonic reactions. E) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. 24) When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated? A) It is used to power yet more cellular work. B) It is lost to the environment. C) It is transported to specific organs such as the brain. D) It is used to generate ADP from nucleotide precursors. E) It is used to store energy as more ATP. 24) 5
25) Which of the following statements regarding enzymes is true? 25) A) Enzymes change the equilibrium point of the reactions they catalyze. B) Enzymes make the rate of a reaction independent of substrate concentrations. C) Enzymes increase the rate of a reaction by lowering the activation energy barrier. D) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. E) Enzymes increase the rate of a reaction by making the reaction more exergonic. 26) The active site of an enzyme is the region that 26) A) binds noncompetitive inhibitors of the enzyme. B) is inhibited by the presence of a coenzyme or a cofactor. C) binds allosteric regulators of the enzyme. D) is involved in the catalytic reaction of the enzyme. 27) Mutations that result in single amino acid substitutions in an enzyme 27) A) may, in rare cases, cause the enzyme to run reactions in reverse. B) will almost always destroy the activity of the enzyme. C) may affect the physicochemical properties of the enzyme such as its optimal temperature and ph. D) will often cause a change in the substrate specificity of the enzyme. E) can have no effect on the activity or properties of the enzyme. 28) Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A) insufficient cofactors B) denaturization of the enzyme C) allosteric inhibition D) saturation of the enzyme activity E) competitive inhibition 29) The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as A) feedback inhibition. B) reversible inhibition. C) metabolic inhibition. D) noncooperative inhibition. E) allosteric inhibition. 28) 29) 30) Some bacteria are metabolically active in hot springs because 30) A) they are able to maintain a lower internal temperature. B) their enzymes have high optimal temperatures. C) their enzymes are completely insensitive to temperature. D) high temperatures make catalysis unnecessary. E) they use molecules other than proteins or RNAs as their main catalysts. 6
31) How do cells use the ATP cycle shown in the figure? 31) A) Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP hydrolysis. B) Cells use the cycle to recycle ADP and phosphate. C) Cells use the cycle primarily to generate heat. D) Cells use the cycle to generate or consume water molecules as needed. E) Cells use the cycle to recycle energy released by ATP hydrolysis. 32) What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A) catabolic pathways B) fermentation pathways C) bioenergetic pathways D) thermodynamic pathways E) anabolic pathways 33) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction A) gains electrons and gains potential energy. B) neither gains nor loses electrons, but gains or loses potential energy. C) gains electrons and loses potential energy. D) loses electrons and gains potential energy. E) loses electrons and loses potential energy. 32) 33) 34) When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes A) oxidized. B) dehydrogenated. C) hydrolyzed. D) reduced. E) redoxed. 34) 35) Where does glycolysis take place in eukaryotic cells? 35) A) mitochondrial inner membrane B) mitochondrial intermembrane space C) cytosol D) mitochondrial matrix 36) The oxygen consumed during cellular respiration is involved directly in which process or event? 36) A) the citric acid cycle B) the phosphorylation of ADP to form ATP C) accepting electrons at the end of the electron transport chain D) glycolysis 7
37) Which step of the citric acid cycle requires both NAD+ and ADP as reactants? 37) A) step 1 B) step 2 C) step 3 D) step 4 38) Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent? 38) A) the citric acid cycle B) chemiosmosis C) electron transport D) glycolysis E) oxidative phosphorylation 39) The processes of photosynthesis and cellular respiration are complementary. During these energy conversions, some energy is A) lost in the form of heat. B) used to create light. C) saved in the chemical bonds of water, CO2 and O2. D) destroyed when the chemical bonds of glucose are made. 39) 8
40) Which H+ ion has just passed through the inner mitochondrial membrane by diffusion? 40) A) hydrogen ion A B) hydrogen ion B C) hydrogen ion C D) hydrogen ion D 41) During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is A) transferred to ADP, forming ATP. B) used to phosphorylate fructose to form fructose 6-phosphate. C) stored in the NADH produced. D) retained in the two pyruvates. E) transferred directly to ATP. 42) Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate? A) oxaloacetate B) citrate C) glyceraldehydes-3-phosphate D) acetyl CoA E) lactate 41) 42) 43) During aerobic respiration, electrons travel downhill in which sequence? 43) A) glucose ATP electron transport chain NADH B) glucose pyruvate ATP oxygen C) food citric acid cycle ATP NAD+ D) food NADH electron transport chain oxygen E) food glycolysis citric acid cycle NADH ATP 44) Where are the proteins of the electron transport chain located? 44) A) mitochondrial intermembrane space B) mitochondrial outer membrane C) cytosol D) mitochondrial inner membrane 9
45) In cellular respiration, the energy for most ATP synthesis is supplied by 45) A) transferring electrons from organic molecules to pyruvate. B) generating carbon dioxide and oxygen in the electron transport chain. C) a proton gradient across a membrane. D) converting oxygen to ATP. E) high energy phosphate bonds in organic molecules. 46) Where is ATP synthase located in the mitochondrion? 46) A) electron transport chain B) outer membrane C) inner membrane D) mitochondrial matrix E) cytosol 47) Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth? A) Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere. B) Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya. C) Glycolysis is found in all eukaryotic cells. D) Glycolysis neither uses nor needs O2. E) The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle. 48) Which kind of metabolic poison would most directly interfere with chemiosmosis and ATP synthesis? A) an agent that reacts with NADH and oxidizes it to NAD+ B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that blocks the passage of electrons along the electron transport chain 49) The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A) oxygen. B) pyruvate. C) NAD+. D) ADP. E) water. 47) 48) 49) 50) If ATP accumulates in a cell 50) A) the rate of cellular respiration does not change. B) feedback inhibition speeds up cellular respiration. C) feedback inhibition slows down cellular respiration. D) the cell receives a signal that there is a need for more energy. 10